In the console Skylanders games, changing which Skylander you had in the game was a simple interaction: take the existing Skylander figure off the connected Portal Of Power accessory, and then place a new one down. Instant swap.
When we were developing the Nintendo 3DS version of the first game, "Skylanders: Spyro's Adventure", we knew the Magic Moment would be more complex, since the 3DS' Portal Of Power wouldn't be connected to the game all the time.
To make gameplay more convenient while on-the-go, we created the "Shadow Zone" - a limbo area, between Earth and the Skylands - where Skylanders could be held in crystals, ready for play. When a player wanted to bring in a new Skylander, they had to approach a dedicated character in the game's hub world... ...and then we needed to come up with an interaction that felt good.
Here's the animated storyboard I devised...
...and here's how it looked in-game: